Multi-output chopper circuit for input power supplies of five-level inverter

In the fields such as various electric power compensators and ac motor drives, large capacity and high-performance converters are wished to be put into practical applications. For these converters, since the upper limit of the switching frequency is low and capacity of device is insufficient, method of connecting the device in series and parallel would be effective. From such reasons, for improving the harmonic characteristics, various multi-level inverters have been reported, in which it is necessary to provide some dc power supplies connected in series that is disadvantage for this inverter. We propose a simple dc-dc converter for adjusting the power supply voltages of this inverter. By means of this dc-dc converter circuit, the voltages of four dc power supplies of five-level inverter can be suitably controlled towards a desired value. The circuit characteristics are discussed by theoretical and simulated procedures. The theoretical results and the simulated ones agree with each other.